I have an S70 and replace the rotors on the on the second replacement of the pads. Since you are in Arlington, check the prices of Olympic Auto Parts. I got some good prices on rotors.

If the rotors still have more than a third left, I might keep them. If they are less than a third and you do lots of heavy braking, it may be better to replace them early since they will dissipate heat better and prevent brake fade due to heat buildup.

Like tires, do you really want to go down to 2/32th inch during the heavy rain at highway speeds? Usually it is when someone crashes that they wish they replaced parts sooner.

My thoughts...why replace the existing rotors if they are still useable, unless you like to throw money down the drain? From what I have experienced and read of others here, stay with stock everything. I see so many people that try aftermarket components only to find they talk of problems down the road. You should be able to get two sets of pads from each rotor in use before replacing the rotor.

Still it is your choice.